痰を押し込むと早死に

一般の方とかガチの医療職でない方を対象に想定しているので、ぼくの経験論ばかりのこのブログだが、たまにはアカデミックな論文も読んでみよう。

 NEJM 372;23 June 4, 2015　

http://www.nejm.org/doi/pdf/10.1056/NEJMoa1503326 High-Flow Oxygen through Nasal Cannula in Acute Hypoxemic Respiratory Failure 

挿管しての人工呼吸管理と、鼻から高流量の酸素を流した場合の両者をガチンコ比較。

 Whether noninvasive ventilation should be administered in patients with acute hypoxemic respiratory failure is debated. Therapy with high-flow oxygen through a nasal cannula may offer an alternative in patients with hypoxemia.

先のエントリーでもら書いたNPPVと、鼻から大量の酸素を流すマシンNHFとの比較。

METHODS 

We performed a multicenter, open-label trial in which we randomly assigned patients without hypercapnia who had acute hypoxemic respiratory failure and a ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen of 300 mm Hg or less to high-flow oxygen therapy, standard oxygen therapy delivered through a face mask, or noninvasive positive-pressure ventilation. The primary outcome was the proportion of patients intubated at day 28; secondary outcomes included all-cause mortality in the intensive care unit and at 90 days and the number of ventilator-free days at day 28. 

シビアな呼吸不全の患者をふりわけて、NPPVかNHFか、はたまた普通の酸素投与ではどうかを比べたというもの。

RESULTS 

A total of 310 patients were included in the analyses. The intubation rate (primary outcome) was 38% (40 of 106 patients) in the high-flow–oxygen group, 47% (44 of 94) in the standard group, and 50% (55 of 110) in the noninvasive-ventilation group (P=0.18 for all comparisons). The number of ventilator-free days at day 28 was significantly higher in the high-flow–oxygen group (24±8 days, vs. 22±10 in the standard-oxygen group and 19±12 in the noninvasive-ventilation group; P=0.02 for all comparisons). The hazard ratio for death at 90 days was 2.01 (95% confidence interval [CI], 1.01 to 3.99) with standard oxygen versus high-flow oxygen (P=0.046) and 2.50 (95% CI, 1.31 to 4.78) with noninvasive ventilation versus high-flow oxygen (P=0.006).

挿管せざるをえなくなったのが、NHFで38%、対照群で47%、NPPVで50%。28病日で人工呼吸器がいらなくなった割合は、NHFで有意に高かった。

CONCLUSIONS 

In patients with nonhypercapnic acute hypoxemic respiratory failure, treatment with high-flow oxygen, standard oxygen, or noninvasive ventilation did not result in significantly different intubation rates. There was a significant difference in favor of high-flow oxygen in 90-day mortality. (Funded by the Programme Hospitalier de Recherche Clinique Interrégional 2010 of the French Ministry of Health; FLORALI ClinicalTrials.gov number, NCT01320384.)

1型呼吸不全では、NPPV、NHF、普通の酸素投与で挿管になってしまった割合は差がなかった。が、90日後の死亡率には有意な差があった。

グラフが示されているけれど、加圧して酸素を押し込む呼吸補助は予後を良くしないという。この商売をやってるぼくらには軽く衝撃であった。圧をかけることで痰を気管支の奥深くに押し込むためというのも一因ではなかろうか。